Physics

Electron

Spin Hall effect

Rashba effect

Laser

Ferromagnetism

Terahertz radiation

Optics

Semiconductor

Femtosecond

Spintronics

Spin polarization

Ultrashort pulse

Materials science

Condensed matter physics

Helicity

Spin (aerodynamics)

Quantum mechanics

Optoelectronics

Electric field

Thermodynamics

Physical Review Letters

We show that a femtosecond spin-current pulse can generate terahertz (THz) transients at Rashba interfaces between two nonmagnetic materials. Our results unambiguously demonstrate the importance of the interface in this conversion process that we interpret in terms of the inverse Rashba Edelstein effect, in contrast to the THz emission in the bulk conversion process via the inverse spin-Hall effect. Furthermore, we show that at Rashba interfaces the THz-field amplitude can be controlled by the helicity of the light. The optical generation of electric photocurrents by these interfacial effects in the femtosecond regime will open up new opportunities in ultrafast spintronics.

Control of Terahertz Emission by Ultrafast Spin-Charge Current Conversion at Rashba Interfaces